Conventional surge arresters protect underground and overhead electrical systems from transient over-voltage surges from lightning, switching, and the like. Traditionally, a 200 Ampere (200 A) elbow arrester configuration is used to address the surges. In this configuration, the bushing of the desired apparatus designed to protect against the surges is connected to a first portion of the elbow connection. An arrester, typically consisting of metal oxide varistor (MOV) elements, is positioned in the second portion of the elbow connector. The MOV elements and bushing are electrically connected in an intermediate portion of the first part of the elbow connection. A ground connecter—which is positioned at an end of the second portion of the elbow connector—is electrically connected to the MOV on a first end and coupled to an external ground on a second end. Therefore, a voltage is applied across the MOV elements from the bushing connection of the apparatus and ground. At steady state, the MOV elements have a relatively high impedance, however as the voltage applied across the elements increases, such as from a lightning surge, the impedance of the MOV elements decreases until a breakdown voltage, wherein the impedance rapidly decreases towards zero. As a result, the MOV elements become highly conductive and serve to conduct transient current from the surge voltage to ground, thereby protecting the apparatus. Such elbow arrester configurations include a pulling eye, which enables a lineman to install and remove the arrester utilizing a fiberglass hot stick attached to the pulling eye.
In applications of higher loads than 200 A, the resulting 600 A connector system requires an adapter known as a load break reducing tap plug (LRTP), which, in conjunction with an extender is coupled to the first portion of the 200 A elbow arrester. The inherent disadvantages of using such a system is that the additional parts introduce installation complexities and fault points for the system.
Such inherent disadvantages in known systems has not been entirely ignored in the industry. In response a T-Body surge arrester with an integrated 600 ampere (600 A) bushing was developed, thereby removing the need for the 600 A/200 A LRTP, and extender. An example of a T-body surge arrester configuration can be found in issued patent Yaworski et al. U.S. Pat. No. 8,018,707 entitled “High Amperage Surge Arrestors.” As discussed in the Yaworski et al. disclosure, a T-body elbow arrester comprises an elbow body having a first portion and a second portion extending from an intermediate section of the first portion in a generally perpendicular direction to define the T-shape. A surge arrester is position in the second portion and an end cap assembly—positioned at an end of the second portion—is electrically connected to the surge arrester. A bushing receiving portion region is positioned on a first end of the first portion of the elbow body, while an insulating plug extends from the intermediate portion of the first portion to a second end of the first portion of the elbow body. An end of the insulating plug is located in the intermediate portion of the elbow body to be coupled to secure the T-body elbow arrester in the assembly.
A disadvantage of the configuration disclosed in Yaworski et al. is that the initial connection of an arrester connected to the bushing receiving area must be removed in order to connect a power cable via a T-body elbow to the same connection point. Another method of installing a power cable via a 600 A elbow to the arrester of Yaworski would be to remove the insulating plug (thereby loosening the connection to the bushing), install another accessory device known as a connecting plug, and then install the new 600 A elbow and power cable.
Therefore, there is a need in the art for an arrester configuration, with a receiving feature that can be mounted directly to an apparatus, such as a bushing or connector accessory. It is preferred that such an apparatus further include a built in male feature designed to allow connection to another accessory.
In addition, there is a need for a coupling fastener positioned in the arrester that allows an apparatus coupled to the coupling fastener to be decoupled without loosening the connection of another apparatus coupled to the elbow body.
Furthermore, there is a need for an insulating cap that couples with the male feature. When the insulating cap is removed the male feature can then be coupled to another accessory, without loosening the connection of an apparatus coupled to the receiving feature.